KR20120081225A - Method of converting c9 aromatics-comprising mixtures to xylene isomers - Google Patents

Abstract

Disclosed herein are methods of making xylene isomers. More specifically, the process comprises contacting a C ₉ aromatic-comprising feed with a catalyst and subjecting the xylene isomer from the intermediate product stream under conditions suitable to convert the feed to an intermediate product stream comprising xylene isomers. Separating at least a portion and recycling the xylene isomer-free intermediate product stream to the feed. Alternatively, the process for preparing the xylene isomers is less than about 30 weight percent C ₉ aromatics and benzene based on the total weight of the feed under conditions suitable for converting the feed to a product stream comprising xylene isomers. Contacting the comprising feed with a non-sulfurized, pore-sized zeolite impregnated with a Group VIB metal oxide. The process disclosed is based on the production of the conversion: xylene isomers to ethylbenzene, xylene isomers to C ₉ aromatics (eg, methylethylbenzene), xylene isomers to C ₁₀ aromatics, trimethylbenzene to methylethylbenzene, benzene to An unexpectedly high proportion of ethylbenzene, and a high conversion of C ₉ aromatics and methylethylbenzene.

Description

METHODS OF CONVERTING C９ AROMATICS-COMPRISING MIXTURES TO XYLENE ISOMERS}

The present invention generally relates to catalytic conversion of aromatic hydrocarbons, and more particularly to disproportionation and alkyl exchange of benzene, toluene, and C ₉ aromatics with xylene isomers.

Brief description of the related technology

C ₈ aromatic containing hydrocarbon mixtures are often products of refinery processes, including, but not limited to, catalytic reforming processes. The reformed hydrocarbon mixtures typically contain the majority of the C _{6 -11} aromatic and paraffin, and its aromatic C _{7 -9} aromatic. The aromatic can be fractionated into its main group, namely C ₆ , C ₇ , C ₈ , C ₉ , C ₁₀ , and C ₁₁ aromatics. C _8, based on the total weight of the aromatic fraction of about 10 weight percent (wt%) to non containing about 30% by weight aromatic is present in the C ₈ aromatics fraction. The balance of the fraction consists of C ₈ aromatics.

Most commonly present among C ₈ aromatics include ethylbenzene ("EB"), and meta-xylene ("mX"), ortho-xylene ("oX"), and para-xylene ("pX") Xylene isomers. Together, in the art and herein, xylene isomers and ethylbenzene are combined and referred to as "C ₈ aromatics." Typically, C _8, if present in the aromatics, ethylbenzene is present in a concentration of about 15% to about 20% by weight, based on the total weight of the C ₈ aromatics, the balance (e.g., about 100% by weight Hereinafter) is a mixture of xylene isomers.

The three xylene isomers typically comprise the remaining C ₈ aromatics and are generally present in an equilibrium weight ratio of about 1: 2: 1 (oX: mX: pX). Thus, as used herein, the term “equilibrated mixture of xylene isomers” refers to a mixture containing isomers in a weight ratio of about 1: 2: 1 (oX: mX: pX).

The product (or reformate) of a catalytic reforming process contains a C _{6 -8} aromatic (that is, the benzene rolled as "BTX", toluene, and C ₈ aromatic). By-products of the process include hydrogen, light gas, paraffins, naphthenes, and of C _{9 +} aromatics. BTX (particularly toluene, ethylbenzene, and xylene) present in reformate oils are known to be useful gasoline additives. However, for environmental and health reasons, the presence of certain aromatics (especially benzene) in gasoline has been greatly reduced and has been considered unpretentious. Nevertheless, the constituent parts of the BTX can be separated from downstream unit operations for use in other capacities. Alternatively, benzene can be separated from BTX and the product mixture of toluene and C ₈ aromatics can be used, for example, as an additive to promote the octane number of gasoline.

Benzene and xylene (particularly para-xylene) are valued higher than toluene due to their usefulness in the preparation of other products. For example, benzene can be used to prepare styrene, cumene, and cyclohexane. Benzene is also useful for the preparation of rubbers, lubricants, dyes, detergents, drugs, and fungi. Among the C ₈ aromatics, when ethylbenzene is the reaction product of ethylene and benzene, such ethylbenzene is generally useful for the preparation of styrene. However, due to purity issues, the ethylbenzene produced as a result of the transalkylation and / or disproportionation reactions cannot be used for styrene production. Meta-xylene itself is useful for the production of isophthalic acid, which is useful in the production of special polyester fibers, paints, and resins. Ortho-xylene is useful for the preparation of phthalic anhydride, which is itself useful for the preparation of phthalate-based plasticizers. Para-xylene is a useful raw material for the preparation of terephthalic acid and esters used in the preparation of polymers such as poly (butene terephthalate), poly (ethylene terephthalate), and poly (propylene terephthalate). While ethylbenzene, meta-xylene, and ortho-xylene are useful raw materials, the demand for the chemicals and materials prepared therefrom is as large as the demand for materials produced from para-xylene and para-xylene. not.

Benzene and C ₈ aromatics, and further in view of the high value, and de-alkylation of toluene to benzene, toluene and placed on the product to be produced therefrom and disproportionated fire to benzene and C ₈ aromatics, toluene and C _{9 +} containing an aromatic C A method for alkyl exchange with ₈ aromatics has been developed. Such methods are generally described in Kirk Othmer's "Encyclopedia of Chemical Technology," 4th Ed., Supplement Volume, pp. 831-863 (John Wiley & Sons, New York, 1995).

Specifically, the toluene disproportionation reaction (“TDP”) is a catalytic method in which 2 moles of toluene are converted into 1 mole of xylene and 1 mole of benzene as follows:

.

.

Other disproportionation reactions include a catalytic process that converts 2 moles of C ₉ aromatics into 1 mole of toluene and a heavy hydrocarbon component (ie, C _{10 +} heavy) as follows:

.

.

Toluene alkyl exchange is a reaction between 1 mole of toluene and 1 mole of C ₉ aromatics (or higher aromatics) to produce 2 moles of xylene as follows:

.

.

Other alkyl exchange reactions involving C ₉ aromatics (or higher aromatics) include reactions using benzene to produce toluene and xylene, as follows:

.

.

As indicated in the above reactions, methyl and ethyl groups bonded to C ₉ aromatic and xylene molecules are generally bonded to any usable ring-forming carbon atom to form various isomeric forms of the molecule. It is shown that this can be found. The mixture of xylene isomers may be further separated into its constituent isomers in the downstream process. Once separated, the isomers can be further processed (eg isomerized) and recycled to yield, for example, substantially pure para-xylene.

In theory and in view of the reactions described above, mixtures comprising C ₉ aromatics may be converted to xylene and / or benzene. The mixture of xylene and benzene can be separated from one another, for example by fractional distillation. However, previously it is not known how the reaction can be carried out in a manner obtainable from a given feed comprising pure C ₉ aromatics.

US Patent No. 5,907,074, each assigned to Phillips Petroleum Company ("Phillips");5,866,741;5,866,741;5,866,742;5,866,742; No. 5,804,059 and a generally C _{9 +} aromatic-containing feed is specific fluid discloses a disproportionation reaction and transalkylation reaction are converted to BTX. Although the patent states that the origin of the fluid feed is not critical, each typically derives from the middle fraction of the product obtained by hydrocarbon (especially gasoline) aromatization reactions carried out in a fluid catalytic cracking ("FCC") unit. Shows a strong preference for the fluid feed being made. Liquid feeds containing low-value, large (or long) hydrocarbons can vaporize in the FCC unit and form a product that can be miscible with high-value diesel fuel and high-octane gasoline in the presence of a suitable catalyst. It can be broken down into light molecules. By-products of the FCC unit include fractions in the low-value, liquid that constitute a preferred fluid feed in accordance with the patent. The very origin of the preferred fluid feed suggests that the feed comprises sulfur-comprising compounds, paraffins, olefins, naphthenes, and polycyclic aromatics (“polyaromatics”).

According to the '074 patent, BTX is generally substantially absent from the preferred feed there, so that significant transalkylation of BTX does not occur as a side reaction to primary disproportionation and transalkylation. The primary reactions described therein are hydrogen-containing fluids and active modifiers (ie, sulfur, silicon, phosphorus, boron, magnesium, tin, titanium zirconium, germanium, indium, lanthanum, oxides of cesium, and combinations of two or more thereof). Is generated in the presence of a catalyst comprising a metal oxide-promoted, Y-type zeolite incorporated therein. Activity modifiers help to counteract the inert (or toxic) effects of sulfur-comprising compounds on metal oxide injection catalysts.

According to the '741,' 742, and '059 patents, BTX is generally substantially absent from the preferred feed therein, so that the significant transalkylation of BTX is a side reaction to the first disproportionation and transalkylation reactions. Does not occur. However, BTX is, there may be the case where the alkylation of the chemical by the C _{9 +} aromatic required secondary. According to the '741 patent, the primary and secondary reactions are carried out in the presence of a hydrogen-containing fluid and a catalyst comprising a beta-type zeolite incorporating an activity promoter (e.g., molybdenum, lanthanum, and oxides thereof). Occurs. According to the '742 patent, the primary and secondary reactions take place in the presence of a hydrogen-containing fluid and a catalyst comprising a beta-type zeolite incorporating metal carbide therein. According to the '059 patent, the primary and secondary reactions take place in the presence of a hydrogen-containing fluid and a catalyst comprising a metal oxide-promoted, mordenite-type zeolite.

The technical purpose to support the respective teachings of the foregoing patents is to convert C _{9 +} aromatics to BTX. For this purpose, the patent discloses certain combinations of fluid feeds, catalysts and reaction conditions suitable for obtaining BTX. However, the patent does not disclose or teach a method for obtaining any single BTX component (much less xylene isomer) except for other BTX components. For each of the above, the presence of sulfur in the fluid feed damages the metal or metal oxide in the catalyst to metal sulfides over time. Metal sulfides have much lower hydrogenation activity than metal oxides, so sulfur reduces the activity of the catalyst.

Moreover, the presence of olefins, paraffins, and polyaromatics in the feed quickly deactivates the catalyst and converts it into unnecessary light gases.

Unlike the foregoing patents, U.S. Patent Application Publication No. 2003/0181774 A1 (Kong, etc.) discloses a transalkylation method of catalytically converted to benzene and C _{9 +} aromatics into toluene and C ₈ aromatics. According to Kong et al., The process must be carried out in the presence of hydrogen in a gas-solid phase fixed-bed reactor having an alkyl exchange catalyst comprising H-zeolite and molybdenum. The object described behind the process of Kong et al. Maximizes the production of toluene used continuously as feed in the downstream selective disproportionation reactor, and obtains the C ₈ aromatic by-product obtained as feed in the downstream isomerization reactor. Is to use P-toluene in the like Kong-selective disproportionation reaction of xylene, how to a mixture of benzene and C _{9 +} aromatic para-propose how to ultimately converted to xylenes. However, the above proposal disadvantageously requires multiple reaction vessels (e.g., an alkyl exchange reactor, and a disproportionation reaction reactor) and, importantly, results from the alkyl exchange reaction, while simultaneously minimizing the production of toluene and ethylbenzene. It does not teach how to maximize the amount of xylene isomers.

US Patent Application Publication No. 2003/0130549 A1 (Xie et al.) Discloses toluene and C to selectively disproportionate toluene to obtain benzene and para-xylene rich xylene isomer streams, and to obtain benzene and xylene isomers. A method of alkylating a mixture of _{9 +} aromatics is disclosed. According to Xie et al., The presence of hydrogen in separate reactors each containing a suitable catalyst (ie, ZSM-5 catalyst for selective disproportionation reaction and mordenite, MCM-22 or beta-zeolite for transalkylation reaction) Under different reactions. Using a downstream process, para-xylene is obtained from the resulting xylene isomers. The process disclosed by Xie et al. Shows that large amounts of benzene and ethylbenzene are preferably produced. However, Xie et al. Do not propose a method of maximizing the amount of xylene isomers generated from the transalkylation reaction, while simultaneously minimizing the production of benzene and ethylbenzene.

U.S. Patent Application Publication No. 2001/0014645 A1 (Ishikawa, etc.) of the disproportionation reaction, for use as a gasoline additive, C _{9 +} aromatics toluene and C _{9 +} aromatics and the transalkylation of toluene to benzene and C ₈ aromatics The method is disclosed. The use of benzene as a reagent in the transalkylation reaction suggests an attempt by Ishikawa et al to remove benzene from low-value gasoline fractions. In the above uses and suggestions for the removal of benzene from gasoline, those skilled in the art will need ethylbenzene in C ₈ aromatics to maximize gasoline yield. Moreover, those skilled in the art will take steps to ensure that the resulting ethylbenzene is not inadvertently broken up with -benzene removed from the gasoline fraction. The reactions described are carried out in the presence of hydrogen and preferably sulfided pore-sized zeolites containing Group VIB metals. In general, a portion of the benzene and C _{9 +} aromatics is typically converted to a product stream containing the BTX. From the BTX product stream, benzene is removed and recycled back to the feed. Ultimately, toluene and C ₈ aromatics are obtained from the benzene / C _{9 +} aromatic feed. The transalkylation reaction is carried out with high molar excess of benzene to C _{9 +} aromatics (ie 5: 1 to 20: 1) to yield toluene and C ₈ aromatics (including ethylbenzene). However, Ishikawa et al. Do not propose a method of maximizing the amount of xylene isomers produced in the transalkylation reaction while minimizing the production of toluene, benzene, and C ₁₀ aromatics.

In general, the prior art does not sufficiently teach or suggest to those skilled in the art how to obtain xylene isomers from mixtures containing C ₉ aromatics and, optionally, toluene and benzene.

Summary of the Invention

Disclosed herein are methods of making xylene isomers. More specifically, the process comprises contacting the feed with a catalyst under conditions suitable to convert the C ₉ aromatic-comprising feed into an intermediate product stream comprising xylene isomers, and from the intermediate product stream a portion of the xylene isomers. Separation of the phase and recycling the xylene isomer-free intermediate product stream to the feed.

In one embodiment, the process for preparing xylene isomers comprises C ₉ aromatics and less than about 30 weight percent benzene (based on the total weight of the feed) under conditions suitable for converting the feed to a product stream comprising xylene isomers. Contacting a non-sulfurized, pore-sized zeolite containing a Group VIB metal oxide.

In another embodiment, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers is suitable to obtain a weight ratio of xylene isomers to ethylbenzene in the product stream at least about 6 to 1. Contacting the feed with a catalyst under conditions.

In a further embodiment, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers results in obtaining at least about 1 to 1 weight ratio of xylene isomers to methylethylbenzene in the product stream. Contacting the feed with a catalyst under suitable conditions.

In another embodiment, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers results in obtaining a weight ratio of xylene isomers to C ₁₀ aromatics in the product stream at least about 3 to 1. Contacting the feed with a catalyst under suitable conditions.

In yet another embodiment, the process of converting the C ₉ aromatic-comprising feed to a product stream containing xylene isomers results in obtaining a weight ratio of trimethylbenzene to methylethylbenzene in the product stream at least about 1.5 to 1. Contacting the feed with a catalyst under suitable conditions.

In still further embodiments, the method of converting the C ₉ aromatic-comprising feed into a product stream containing xylene isomers is suitable to obtain a weight ratio of benzene to ethylbenzene in the product stream at least about 2 to 1. Contacting the feed under catalyst.

In a further embodiment, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers comprises at least about a weight ratio of C ₉ aromatics present in the feed to C ₉ aromatics present in the product stream. Contacting the feed with a catalyst under conditions suitable to obtain four to one.

In still further embodiments, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers comprises the step of weighting the weight ratio of methylethylbenzene in the feed to methylethylbenzene present in the product stream at least about 2. Contacting the feed with a catalyst under conditions suitable to obtain on a one-to-one basis.

Further features of the present invention will become apparent to those skilled in the art upon reviewing the following detailed description, taken in conjunction with the drawings, examples, and appended claims.

For a more complete understanding of the invention, reference will be made to the detailed description and the accompanying drawings, in which:
1 is a general diagram of equipment that may be used to perform the disclosed method;
2 is a process induction scheme of steady state conversion of C ₉ aromatics generally using a mordenite catalyst;
3 is a process flow diagram of the steady state conversion of C ₉ aromatics generally using molybdenum-impregnated mordenite catalysts.
While the disclosed methods may accommodate embodiments in various forms, specific embodiments of the invention are illustrated in the drawings (to be described below), the disclosures being exemplary, and the invention being specific to and described herein. It should be understood that it is not intended to limit the implementation.

The present invention generally relates to a process for preparing xylene isomers which is particularly suitable as a chemical feed for the production of para-xylene. More specifically, the process comprises contacting the feed with a catalyst under conditions suitable for converting the C ₉ aromatic-comprising feed to an intermediate product stream comprising xylene isomers and removing the xylene isomer from the intermediate product stream. Separating at least a portion and recycling the xylene isomer-free intermediate product stream to the feed. Alternatively, the process for preparing xylene isomers comprises a non-sulfurized, pore fed feed comprising Group C8 aromatics containing less than about 30 weight percent benzene based on the total weight of the C ₉ aromatics and the feed. Contacting the large zeolite with the feed under conditions suitable to convert the feed into a product stream comprising xylene isomers.

Suitable feeds for use according to the disclosed methods of the invention include those ultimately obtained from the crude oil purification process. In general, crude oil is desalted and then distilled into various components. The desalting step generally removes metals and suspended solids that may cause catalyst deactivation in downstream processes. The product obtained from the desalting step is subjected to atmospheric or vacuum distillation. Among the fractions obtained through atmospheric distillation are crude or virgin naphtha, gasoline, kerosene, light fuel oil, diesel oil, gas oil, lubricating oil distillate, and heavy residues, which are often further distilled through vacuum distillation methods. Many of these fractions can be sold as end products, or by breaking up hydrocarbon molecules into smaller molecules and combining them to form larger, higher-value molecules, or hydrocarbon molecules into higher-value molecules. Again, it can be further processed in downstream unit operations that can change the molecular structure of hydrocarbon molecules. For example, crude or virgin naphtha obtained from the distillation step removes impurities such as sulfur, nitrogen, oxygen, halides, heteroatoms, and metal impurities that can convert olefins to paraffins and deactivate downstream catalysts. Can be passed with the hydrogen through a hydrotreating unit. Leaving the hydrotreatment unit is a treated gas that is free or substantially free of impurities, hydrogen-rich gas, and a stream containing hydrogen sulfide and ammonia. Light hydrocarbons are sent to downstream unit operations ("reformers") which convert the hydrocarbons (eg non-aromatics) into hydrocarbons (eg aromatic) with better gasoline properties. In general, aromatic processed gas containing (typically located in the boiling range of C _{6 -10} aromatic) may serve as a feed suitable for conversion in accordance with the method of the disclosed invention.

Alternatively, the hydrocracking unit may take a feed similar to that sent to the FCC unit, converting such feed to light hydrocarbons having poor gasoline properties (ie naphtha), and without sulfur or olefins I rarely switch. Next, the light hydrocarbons are sent to the reformer so that the hydrocarbons are converted to hydrocarbons (eg aromatic) having better gasoline properties. Outside the reformer is a reformate containing aromatics as well as paraffins (typically located in the boiling range of C _{6 -10} aromatic). Reformates are substantially free of sulfur and olefins, but include paraffins and polyaromatics. Thus, in a subsequent step, the paraffins and polyaromatics are removed to give a product stream containing C ₉ aromatics. The product stream can serve as a suitable feed for conversion in accordance with the disclosed process of the invention.

The composition of the crude oil can vary considerably depending on its source. Moreover, feeds suitable for use in accordance with the methods of the invention disclosed herein are typically obtained as products of various upstream unit operations and may, of course, vary depending on the reactants / materials applied to such unit operations. Often, the origin of the reactants / materials will indicate the composition of the feed obtained as the product of the unit operation.

C ₉ aromatic-comprising feeds generally comprise C ₉ aromatics. As used herein, the term "aromatic" refers to the main group of unsaturated cyclic hydrocarbons containing one or more rings represented by benzene, having six-carbon rings containing three double bonds. In general, see “Hawley's Condensed Chemical Dictionary,” at p. 92 (13 'Ed., 1997). As used herein, the term "C ₉ aromatic" means a mixture comprising any aromatic compound having nine carbon atoms. Preferably, the C ₉ aromatic is 1,2,4-trimethylbenzene (pseudomen), 1,2,3-trimethylbenzene (hemimelliten), 1,3,5-trimethylbenzene (mesitylene), meta -Methylethylbenzene, ortho-methylethylbenzene, para-methylethylbenzene, iso-propylbenzene, and n-propylbenzene.

Along with the C ₉ aromatics, the feed will typically contain numerous other hydrocarbons, most of which are present only in trace amounts. For example, the feed will be substantially free of paraffins and olefins. The feed substantially free of paraffins and olefins preferably comprises less than about 3 weight percent of each of the paraffins and olefins, more preferably less than about 1 weight percent of each of the paraffins and olefins, based on the total weight of the feed. Moreover, the feed will be substantially free of sulfur (eg elemental sulfur and sulfur-containing hydrocarbons and non-hydrocarbons). The substantially sulfur free feed preferably comprises less than about 1 weight percent sulfur, more preferably less than about 0.1 weight percent sulfur, and even more preferably less than about 0.01 weight percent sulfur, based on the total weight of the feed. do.

In various preferred embodiments, the feed is substantially free of xylene isomers, toluene, ethylbenzene, and / or benzene. The feed substantially free of xylene isomers preferably comprises less than about 3 weight percent of xylene isomers, more preferably less than about 1 weight percent of xylene isomers, based on the total weight of the feed. The feed substantially free of toluene preferably comprises less than about 5% by weight of toluene, more preferably less than about 3% by weight of toluene, based on the total weight of the feed. The feed substantially free of ethylbenzene preferably comprises less than about 5 weight percent ethylbenzene, more preferably less than about 3 weight percent ethylbenzene, based on the total weight of the feed. The feed substantially free of benzene comprises preferably less than about 5% by weight of benzene, more preferably less than about 3% by weight of benzene, based on the total weight of the feed.

However, in certain embodiments, the feed may comprise a substantial amount of one or both of toluene and benzene. For example, in certain embodiments, the feed may comprise up to about 50 weight percent of toluene based on the total weight of the feed. Preferably, however, the feed is less than about 50 weight percent toluene, more preferably less than about 40 weight percent toluene, even more preferably less than about 30 weight percent toluene, and most preferred, based on the total weight of the feed Preferably less than about 20% by weight of toluene. Similarly, in certain embodiments, the feed may comprise up to about 30 weight percent benzene based on the total weight of the feed. Preferably, however, the feed comprises less than about 30 weight percent benzene, more preferably less than about 20 weight percent benzene, based on the total weight of the feed.

In yet further various embodiments, the feed may be substantially free of C _{10 +} aromatics. However, the feed need not be substantially free of C _{10 +} aromatics. In general, C _{10 +} aromatics (“A ₁₀₊ ”) will include benzene having one or more hydrocarbon functional groups having a total of at least 4 carbons. The above examples of C _{1O +} aromatics are butylbenzene (iso-butylbenzene and include tertiary butyl benzene), C _1O aromatic ( "A _10"), such as diethyl benzene, methyl propyl benzene, dimethyl ethyl benzene, tetramethyl benzene, And C ₁₁ aromatics such as trimethylethylbenzene, and ethylpropylbenzene. Examples of C _{10 +} aromatics also include naphthalene, and methylnaphthalene. The feed substantially free of C _{10 +} aromatics preferably comprises less than about 5 weight percent C _{10 +} aromatics, more preferably less than about 3 weight percent C _{10 +} aromatics, based on the total weight of the feed.

As used herein, the term “C ₈ aromatics” refers to mixtures containing mainly xylene isomers and ethylbenzene. Alternatively, as used herein, the term "xylene isomer" refers to a mixture containing meta-, ortho-, and para-xylene, wherein the mixture is substantially free of ethylbenzene. Preferably, the mixture contains less than 3% by weight ethylbenzene, based on the combined weight of xylene isomers and optional ethylbenze. More preferably, however, the mixture contains less than about 1 weight percent ethylbenzene.

As described above, in some embodiments of the process of the invention, the feed is catalytically converted to an intermediate product stream containing xylene isomers, at least a portion of the xylene isomers are separated from the intermediate product stream, and then The intermediate product stream is recycled to the feed. In the first pass, the product of the conversion is referred to as the "middle product stream", once at least a portion of the xylene isomers are removed therefrom and the stream is recycled. However, in other embodiments, the "intermediate product stream" may be considered as a "product stream" because it contains xylene isomers, which are the particular aromatics that are subsequently pursued in the conversion. Thus, in this embodiment, the process is described as a process wherein the feed is catalytically converted to a product stream containing xylene isomers, the xylene isomers are separated from the product stream, and then the product stream is recycled to the feed. Can be.

In this embodiment, whether referred to as "intermediate product stream" or "product stream", the recycled stream preferably contains no xylene isomers (or contains only minor amounts), mainly unreacted feeds, Toluene, and / or benzene.

In a further embodiment of the process of the invention, the product or intermediate product stream is xylene isomer present in a weight ratio of at least about 6 to 1, preferably at least about 10 to 1, and more preferably at least about 25 to 1. And ethylbenzene. Another process described is a process for converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers, wherein the weight ratio of xylene isomers to ethylbenzene in the product stream is at least about 6 to 1, preferably at least Contacting the feed with a catalyst under conditions suitable to obtain about 10 to 1, and more preferably at least about 25 to 1. This high weight ratio of xylene isomers to ethylbenzene in the product stream is beneficial in downstream processes where the product stream is fractionated into major members, namely aromatics containing 6, 7, 8, and 9 carbons. Typically, further processing of the C ₈ aromatic fraction will necessarily include an energy-consuming process of ethylbenzene. However, if there is substantially no ethylbenzene in the liquid reaction product, and therefore substantially no ethylbenzene in the C ₈ aromatic fraction, the energy-consuming process does not need to remove ethylbenzene from the fraction.

Moreover, it is particularly desired to be substantially free of ethylbenzene. As mentioned previously, although ethylbenzene can be used as a raw material for producing styrene, the ethylbenzene must be in highly purified form. Benzene, toluene, and certain ethylbenzenes resulting from disproportionation and alkylation of C ₉ aromatics are necessarily present in mixtures containing other aromatics. Separation of ethylbenzene from the mixture is very difficult and very expensive. As a result, from a practical point of view, the ethylbenzene cannot be used for the production of styrene. Practically, ethylbenzene will be used as a gasoline additive (as octane booster there), or similarly will be subjected to further disproportionation to yield light gases (eg ethane) and benzene. However, according to the invention, the process will be omitted if there is substantially no ethylbenzene in the liquid reaction product and the C ₈ aromatics.

In another embodiment of the invention, the product or intermediate stream comprises at least about 1 to 1, preferably at least about 5 to 1, and more preferably at least about 10 xylene isomers to methylethylbenzene (MEB) It is contained in the weight ratio of 1. In another method, the method of converting the C ₉ aromatic-comprising feed into a product stream containing xylene isomers comprises a weight ratio of xylene isomers to methylethylbenzene in the product stream of at least about 1 to 1, preferably at least Contacting the feed with a catalyst under conditions suitable to obtain about 5 to 1, more preferably at least about 10 to 1. Lack of methylethylbenzene (or a small amount of methylethylbenzene) in the product and / or intermediate product streams results in less amount of unreacted or produced C ₉ aromatics that need to be recycled to the conversion feed, thus reducing energy It is beneficial in preserving the cost and reducing the cost of capital.

In yet another embodiment of the process of the invention, the product or intermediate product stream comprises at least about 3 to 1, preferably at least about 5 to 1, and more preferably at least about 10 units of xylene isomers to C ₁₀ aromatics. It is contained in the weight ratio of 1. In another method, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers comprises a weight ratio of xylene isomers to C ₁₀ aromatics in the product stream of at least about 3 to 1, preferably at least Contacting the feed with a catalyst under conditions suitable to obtain about 5 to 1, and more preferably at least about 10 to 1. This high proportion is evidence that the dominant reaction associated with C ₉ aromatics is a disproportionation reaction yielding xylene isomers and not a reaction yielding C ₁₀ aromatics, toluene, and benzene. Product and / or intermediate product stream within a C _1O lack of an aromatic (or a small amount of C _1O aromatic) is so further the amount of unreacted or generated C _1O aromatic that need to be recycled to the feed for conversion decreases, thus energy It is beneficial in preserving the cost and reducing the cost of capital. As long as the C ₁₀ aromatics are present in the intermediate or product stream, the C ₁₀ aromatics are predominantly tetramethylbenzene, which can be regenerated and further converted into xylene isomers. Advantageously, the C ₁₀ aromatics do not include many ethyldimethylbenzenes and / or diethylbenzenes, both of which are more difficult to convert to xylene isomers and which are rarely recycled.

In a further embodiment of the process of the invention, the product or intermediate product stream comprises at least about 1.5 to 1, preferably at least about 5 to 1, and even more preferably at least about 15 to 1 trimethylbenzene to methylethylbenzene It is contained in the weight ratio of. In another method, the method comprises converting the C ₉ aromatic-comprising feed into a product stream containing xylene isomers, wherein the weight ratio of trimethylbenzene to methylethylbenzene in the product stream is at least about 1.5 to 1, preferably Preferably, contacting the feed with a catalyst under conditions suitable to obtain at least about 5 to 1, more preferably at least about 10 to 1, and even more preferably at least about 15 to 1. In order to obtain xylene isomers from trimethylbenzene, one methyl group must be removed from the trimethylbenzene molecule. Conversely, in order to obtain xylene isomers from methylethylbenzene, the ethyl group on the benzene ring must be substituted with a methyl group. Such substitutions are difficult to carry out. As a result, the high ratio of trimethylbenzene to methylethylbenzene is advantageous in that trimethylbenzene is easier to convert to xylene isomers than methylethylbenzene and consequently is easier to recycle.

In still further embodiments of the process of the invention, the product or intermediate product stream comprises a weight ratio of benzene to ethylbenzene of at least about 2 to 1, preferably at least about 5 to 1, and more preferably at least about 10 to 1 It contains. In another method, the method of converting a C ₉ aromatic-comprising feed into a product stream containing xylene isomers comprises the weight ratio of benzene to ethylbenzene in the product stream being at least about 2 to 1, preferably at least about 5 1, and more preferably contacting the feed with the catalyst under conditions suitable for obtaining at least about 10 to 1. This high proportion has a lower value as a chemical feed when ethylbenzene of the type obtained during disproportionation and transalkylation involving C ₉ aromatics is difficult to separate ethylbenzene from mixtures of other C ₈ aromatics. In that respect, it is advantageous. As mentioned above, the molecules of C ₉ aromatics and benzene may be alkyl exchanged with molecules of xylene and toluene. Thus, a high ratio of benzene to ethylbenzene in the stream may prove useful when considering that some of the stream can be recycled to increase the yield of xylene isomers.

In another embodiment of the process of the invention, the product or intermediate product stream is at least about 4 to 1, preferably at least about 8 to 1, and more preferably at least about 10 to 1 based on the amount present in the feed. C ₉ aromatics present in the amount (weight ratio). In another method, the method of converting a C ₉ aromatic-comprising feed to a product stream containing xylene isomers comprises a weight ratio of C ₉ aromatics present in the feed to C ₉ aromatics present in the product stream at least about 4 Contacting the feed with a catalyst under conditions suitable for obtaining 1 to 1, preferably at least about 8 to 1, and more preferably at least about 10 to 1. The high conversion is advantageous in that less amount of unreacted C ₉ aromatics that need to be recycled to the feed for conversion are conserved in energy and reduce capital costs.

In yet another embodiment of the process of the invention, the feed is at least about 2 to 1, preferably at least about 10 to 1, and more preferably at least about 20 to the amount present in the product or intermediate product stream It contains methyl ethyl benzene present in the amount (weight ratio) of 1. In another method, the method of converting a C ₉ aromatic-comprising feed into a product stream containing xylene isomers comprises a weight ratio of methylethylbenzene present in the feed to methylethylbenzene present in the product stream of at least about 2 Contacting the feed with the catalyst under conditions suitable for obtaining 1 to 1, preferably at least about 10 to 1, and more preferably at least about 20 to 1. The high ratio is evidence that the process of the present invention effectively converts the high proportion of methylethylbenzene present in the C ₉ aromatics in the feed. Indeed, a high proportion indicates that the reaction effectively converts methylethylbenzene to about 50%, preferably 90%, and most preferably 95%, to light gas and light aromatics. Moreover, this high proportion is evidence that the reaction does not yield methylethylbenzene.

The disclosed method is generally illustrated in FIG. 1, and an embodiment of the method, designated generally 10 , includes reactor 12 and liquid product separator 14. More specifically, the C ₉ aromatic-comprising feed in feed line 16 and the hydrogen-comprising gas in gas line 18 are combined and heated in furnace 20. The heated mixture is passed into reactor 12 where the C ₉ aromatic-comprising feed is catalytically reacted in the presence of hydrogen to yield an intermediate product. The intermediate product exits reactor 12 via intermediate product line 22 and then is cooled in heat exchanger 24. The cooled, intermediate product exits heat exchanger 24 via transport line 26 and passes into vessel 28 where gas and liquid are separated from each other. If desired, fresh hydrogen can also be passed directly into reactor 12 via gas line 18A for the purpose of cooling reactor 12. The gas, which is mainly hydrogen, can be removed from vessel 28, some of which can be compressed (not shown in the compressor), recycled to gaseous hydrogen-comprising gas in line 18 via gas line 30, while the residue can be purged through purge line 32. . The liquid is removed from the vessel 28 via the transport line 34 and passed into the liquid separator 14. In separator 14, the member comprising the intermediate product is separated. The xylene isomer product exits the separator through conduit 36. One or more recycle streams return C ₉ aromatics 38 and benzene and toluene 40 to reactor 12 by, for example, combining these streams with fresh feed in feed line 16. Accordingly, entering this embodiment 10 of the process is a C ₉ aromatic-comprising feed 16 and a hydrogen-comprising gas 18, leaving the process is a xylene isomer product 36. Since the transalkylation and disproportionation reactions carried out in the above process do not require a specific number of methyl groups present relative to the number of benzene groups, some of the formed benzene and toluene 42 can be removed from the overall process, It is not possible to extract any significant amount. The process may also include the use of recycle streams, which are described in more detail below.

Suitable process equipment and conditions necessary for carrying out the method are understood by those skilled in the art to be included in the disclosed methods (and various embodiments thereof). The process equipment, if possible, includes appropriate pipes, pumps, valves, unit operation equipment (e.g., reactor vessels, heat exchangers, separation units, etc. with appropriate inlets and outlets), associated process control equipment, quality control equipment. Including but not limited to. If particularly preferred, any other process equipment is embodied herein.

In general, the disclosed method is carried out in a reaction vessel containing an active catalyst comprising a pore-sized zeolite with Group VIB metal oxide, and a suitable binder, as described in more detail below. Pore-sized zeolites suitable for use according to the invention include zeolites having a pore size of about 6 Angstroms or greater and include beta (BEA), EMT, FAU (e.g., Zeolite X, Zeolite Y (USY)), LTL, MAZ, Magite, Mordenite (MOR), Omega, SAPO-37, VFI, Zeolite L structured zeolite (IUPAC Times of Zeolite Nomenclature). Preferably, however, the pore-sized zeolites used in the present invention include beta (BEA), Y (USY), and mordenite (MOR) zeolites, each of which is a general description thereof. Kirk Othmer's "Encyclopedia of Chemical Technology," 4th Ed., Vol. 16, pp. 888-925 (John Wiley & Sons, New York, 1995) and W.M. Meier et al., “Atlas of Zeolite Structure Types,” 4th Ed. (Elsevier 1996). Zeolites of this type are described, for example, in PQ Corporation (Valley Forge, Pennsylvania), Tosoh USA, Inc. (Grove City, Ohio), and UOP Inc. (Des Plaines, Illinois). More preferably, the large pore-size zeolites used in the present invention are mordenite zeolites.

Any metal oxide capable of promoting hydrodealkylation of C _{9 +} aromatic compounds to C ₆ to C ₈ aromatic hydrocarbons when incorporated into zeolites can be used in the present invention. The metal oxide is preferably selected from the group consisting of molybdenum oxide, chromium oxide, tungsten oxide, and any two or more combinations thereof, wherein the oxidation state of the metal may be in any available oxidation state. For example, for molybdenum oxide, the oxidation state of molybdenum can be 0, 2, 3, 4, 5, 6, or any combination of two or more thereof.

Examples of suitable metal compounds include, but are not limited to, chromium-, molybdenum-, and / or tungsten-containing compounds. Suitable chromium-containing compounds include chromium (II) acetate, chromium (II) chloride, chromium (II) fluoride, chromium (III) 2,4-pentanedionate, chromium (III) acetate, chromium (III) acetylacetonate Chromium (III) chloride, chromium (III) fluoride, chromium hexacarbonyl, chromium (III) nitrate, chromium nitride, chromium (III) perchlorate, and chromium (III) telluride, including It is not limited. Suitable tungsten-containing compounds include, but are not limited to, tungstic acid, tungsten (V) bromide, tungsten (V) chloride, tungsten (VI) chloride, tungsten hexacarbonyl, and tungsten (VI) oxychloride. Molybdenum-containing compounds are preferred metals, which compounds include ammonium dimolybdate, ammonium heptamolybdate (VI), ammonium molybdate, ammonium phosphomolybdate, ammonium tetrathiomolybdate, ammonium tetrathiomolybdate Date, bis (acetylacetonate) dioxomolybdenum (VI), molybdenum fluoride, molybdenum hexacarbonyl, molybdenum oxychloride, molybdenum sulfide, molybdenum (II) acetate, molybdenum (II) chloride, molybdenum (III) bromide , Molybdenum (III) chloride, molybdenum (IV) chloride, molybdenum (V) chloride, molybdenum (VI) fluoride, molybdenum (VI) oxychloride, molybdenum (VI) tetrachloride oxide, potassium molybdate, sodium molybdate Date, and molybdenum oxide, wherein the oxidation state of Mo is 2, 3, 4, 5, and 6 and combinations of two or more thereof It can include, for that), but is not limited thereto. Preferably, the molybdenum is rich in molybdenum with the relative ease of incorporation into the desired mordenite zeolite, so that the metal compound is ammonium molybdate.

The amount of metal or metal oxide present in the catalyst composition should be sufficient for the transalkylation and disproportionation processes to be effective. Accordingly, the amount of metal or metal oxide is preferably from about 0.1% to about 40% by weight, more preferably from about 0.5% to about 20% by weight, and even more preferably, based on the total weight of the catalyst composition From about 1% to 10% by weight. If a combination of metals or metal oxides is used, the molar ratio of second, third, and fourth metal oxides to first metal oxides should range from about 0.01: 1 to about 100: 1.

Molybdenum is a preferred metal and, when present in an amount from about 1% to about 5% by weight, converts unexpectedly and surprisingly better than what is obtained when the amount is outside the above range. The unexpected and surprisingly good results are shown in the examples below. In the above discovery, the catalyst is preferably injected with molybdenum or molybdenum oxide, wherein the molybdenum is comprised between about 0.5% and about 10% by weight of the catalyst based on the total weight of the catalyst. More preferably, molybdenum is included in about 1% to about 5% by weight of the catalyst, based on the total weight of the catalyst, and most preferably, molybdenum is included in about 2% by weight of the catalyst.

Suitable binders for use in the preparation of catalysts are, for example, α-alumina and γ-alumina; Silica; Alumina such as alumina-silica; And combinations thereof. The weight ratio of zeolite to binder is preferably from about 20: 1 to about 0.1: 1, and more preferably from about 10: 1 to about 0.5: 1. The binder is typically combined with the zeolite in the presence of a liquid, preferably an aqueous medium, to form a zeolite-binder mixture.

The catalyst can be used according to the disclosed methods using any suitable method for incorporating a metal oxide compound into the zeolite, such as for example impregnation or absorption. For example, zeolites and binders can be mixed well by stirring, blending, kneading, or effusion, and then the zeolite-binder mixture is about 20 ° C. to about 200 ° C., preferably about 25 ° C. to about 175 ° C. in air. , And more preferably at a temperature in the range of 25 ° C. to 150 ° C. for about 0.5 hour to about 50 hours, preferably about 1 hour to about 30 hours, and more preferably 1 hour to 20 hours. . Preferably, it is mixed under atmospheric pressure, but may be mixed at pressures slightly above and slightly below atmospheric. After sufficient mixing and drying of the zeolite and binder, the zeolite-binder mixture is in the range of about 300 ° C. to 1000 ° C., preferably about 350 ° C. to about 750 ° C., and more preferably about 450 ° C. to about 650 ° C. It can be fired arbitrarily at the temperature of. Firing may be performed for about 1 hour to about 30 hours, and more preferably about 2 hours to about 15 hours, to obtain a calcined zeolite-binder. If no binder is required and the zeolite is also present, the zeolite can be calcined under similar conditions to remove any contaminants.

Zeolites with or without binder and with or without firing are generally first mixed with the metal compound. If the binder is combined with a metal compound, it can then be converted to the metal oxide, generally by heating at elevated temperatures in the atmosphere. The metal is preferably selected from Group VIB metals such as chromium, molybdenum, tungsten, and combinations thereof, as mentioned above. The metal compound may be dissolved in the solvent before contacting the zeolite. However, preferably the metal compound is an aqueous solution. The contact may be carried out at any temperature, but preferably at a temperature of about 15 ° C. to about 100 ° C., more preferably about 20 ° C. to about 100 ° C., and even more preferably about 20 ° C. to 60 ° C. Can be performed. The contact can be carried out generally for a period of time sufficient to obtain a mixture of the metal compound and the zeolite under any pressure, preferably under atmospheric pressure. Generally, the period is from about 1 minute to about 15 hours, preferably from about 1 minute to about 5 hours.

Depending on the strength of the operation and other process variables, the catalyst will age. As the catalyst matures, its activity on the desired reaction tends to decrease slowly due to coke deposition on the surface of the catalyst or the formation of feed toxicity. The catalyst may be maintained at its initial activity level or periodically regenerated to its initial activity level by methods generally known to those skilled in the art. Alternatively, the aged catalyst can simply be replaced with a new catalyst.

As long as the aged catalyst is not replaced with a new catalyst, the aged catalyst may require regeneration once every six months, once every three months, or sometimes once every month, or twice monthly. As used herein, the term "regeneration" means that at least a portion of the molecular sieve initial activity is recovered by burning any coke deposition on the catalyst with oxygen or an oxygen-containing gas. Full literature is available on catalyst regeneration methods that can be used in the process of the invention. Some of these regeneration methods include chemical methods for increasing the activity of inactivated molecular sieves. Other regeneration methods include coke-inactivated catalysts by combustion of coke into an oxygen-containing gas stream, such as a continuous circulation of inert gas containing large amounts of oxygen or a circulating flow of regeneration gas through a catalyst bed in a closed loop device. Relates to how to play.

The catalysts used in the disclosed process are particularly suitable for the regeneration by oxidation or combustion of catalyst deactivated carbonaceous deposits (also known as coke) with oxygen or oxygen-containing gases. Although the method by which the catalyst can be regenerated by coke combustion can vary, it is preferably carried out at conditions of temperature, pressure and gas space velocity which, for example, cause little thermal damage to the regenerated catalyst. In addition, in the case of continuous regeneration methods, in the case of fixed bed reactor systems, it is desirable to regenerate in a predetermined manner to reduce process downtime or equipment size.

Although optimum regeneration conditions and methods are generally known to those skilled in the art, catalyst regeneration is preferably in a temperature range of about 550 ° F. (about 287 ° C.) to about 1300 ° F. (about 705 ° C.), and about 0 pounds per square inch gauge (psig). ) (About 0 mega-Pascal (MPa)) to about 300 psig (about 2 MPa) and a regeneration gas oxygen content of about 0.1 mol% to about 25 mol%. The oxygen content of the regeneration gas may typically be increased over the course of the catalyst regeneration process based on the catalyst bed outlet temperature, which regenerates the catalyst as quickly as possible while avoiding catalyst-damaging process conditions. Preferred catalyst regeneration conditions include temperatures ranging from about 600 ° F. (about 315 ° C.) to about 1150 ° F. (about 620 ° C.), pressures ranging from about 0 psig (about 0 MPa) to about 150 psig (about 1 MPa), and about 0.1 Regeneration gas oxygen content from mol% to about 10 mol%. The oxygen-containing regeneration gas preferably comprises nitrogen and carbon combustion products, such as carbon monoxide and carbon dioxide, to which oxygen in atmospheric form has been added. However, oxygen may be introduced into the regeneration gas as pure oxygen, or as a mixture of oxygen and another gaseous component. Preferably the oxygen containing gas is atmosphere.

As described above, the disclosed method is carried out in the presence of a hydrogen-containing gas comprising hydrogen (ie molecular hydrogen, H ₂ ).

The hydrogen-containing gas preferably contains about 1 volume percent (vol%) to about 100 volume percent, preferably about 50 volume percent to about 100 volume percent, and more preferably 75 volume percent to 100 volume percent of hydrogen. Include in the range of. If the hydrogen content in the gas is less than about 100% by volume, the remainder of the gas will not damage any inert gases such as, for example, nitrogen, helium, neon, and mixtures thereof, or the disclosed methods and catalysts used herein. May be any other gas. Hydrogen may be supplied from a hydrogen plant, catalyst reshaping plant, or other hydrogen-generating or hydrogen-recovery process.

Hydrogen is preferably present during the catalytic reaction with a hydrogen-to-hydrocarbon molar ratio of about 0.01 to about 5, more preferably about 0.1 to about 2, and more preferably about 0.1 to about 0.5. Hydrogen circulation rates below this range may result in higher catalyst deactivation rates resulting in increased and more frequent energy intensive regeneration cycles. Too high a reaction pressure increases energy and equipment costs and reduces marginal gains. Too high a hydrogen circulation rate can also affect the reaction equilibrium and can lead to undesired reactions such as, for example, reduced C ₉ aromatic conversion and lower xylene isomer yields. The presence of an inert gas can act beneficially, reducing the partial pressure of the hydrocarbons leading to higher conversion of the feed to xylene isomers.

Contacting a fluid feed stream containing hydrocarbons with a hydrogen-containing fluid (gas or liquid) in the presence of a catalyst composition is crude or semi-continuous under conditions effective to convert the hydrocarbons to C ₆ to C ₈ aromatic hydrocarbons. Or in a continuous process, it can be carried out in any technically suitable manner. In general, the fluid stream as described above, preferably in the vaporized state, is fixed catalyst bed, by any means known to those skilled in the art, such as, for example, pressure, meter pumps and other similar means. Or with the feed into a suitable hydroprocessing reactor having a mobile catalyst bed, or a fluidized catalyst bed, or any combination of two or more thereof. Since hydrogen processing reactors and methods are well known to those skilled in the art, the description is simply omitted herein.

Conditions suitable for carrying out the process of the invention range from about 0.1 to about 20, preferably from about 0.5 to about 10, and most preferably from about 1 to about 5 unit mass of feed per unit mass of catalyst per hour. And a weight hourly space velocity (WHSV) of the furnace fluid feed stream. Hydrogen-containing fluid (gas) time space velocities generally range from about 1 to about 10,000, preferably from about 5 to about 7,000, and most preferably from about 10 to about 10,000 ft ³ H ₂ / ft ³ catalyst / hour. to be.

Generally, the pressure is about 0.5 MPa (about 73 psig) to about 5 MPa (about 725 psig), preferably about 1 MPa (about 145 psig) to about 3 MPa (about 435 psig), and more preferably From about 1.25 MPa (about 181 psig) to about 2 MPa (about 190 psig). Suitable temperatures for carrying out the process of the present invention are from about 200 ° C. (about 392 ° F.) to about 1000 ° C. (about 1830 ° F.), more preferably from about 300 ° C. (about 572 ° F.) to about 800 ° C. (about 1472 ° F.). And even more preferably in the range of about 350 ° C. (about 662 ° F.) to about 600 ° C. (about 1112 ° F.).

[ Example ]

The following examples are provided to illustrate the invention but are not intended to limit its scope. Example 1 relates to the preparation of a catalyst and is then used in the process described in Examples 2-4. Example 3-A is based on process modeling using the feed and catalyst "A" described in Example 3, while Example 3-B uses the feed and catalyst "B" described in Example 3 It is based on similar process modeling used. Example 5 illustrates the performance of molybdenum-impregnated, pore-sized zeolite catalysts.

Example  One

This example then describes the preparation of two catalysts (catalysts "A" and "B") used in the process described in Examples 2-4. The first catalyst, catalyst "A", is a mordenite zeolite, while the second catalyst, catalyst "B", comprises molybdenum-impregnated, mordenite zeolite. This example also describes the preparation of two other catalysts (catalysts "C" and "D") used in the process described in Example 5. Catalyst "C" included molybdenum-impregnated, beta zeolite, while catalyst "D" included molybdenum-impregnated, USY zeolite.

More specifically, catalyst "A" comprises 80 g of H-mordenite zeolite (sold from Union Carbide Corporation (Houston, Texas) under the trade name "LZM-8") in 100 g of distilled water and an Al ₂ 0 ₃ solution (water Heavy solid 9.3%) (sold as alumina solution from Criterion) and mordenite zeolite prepared by mixing. The mixture was then dried at 329 ° F. (165 ° C.) for about 3 hours and then calcined at 950 ° F. (510 ° C.) for about 4 hours to give a mordenite catalyst (80% sieve / 20% Al ₂ O ₃ ). Obtained. After firing, the catalyst was granulated and passed through a 14/40 sieve.

Catalyst "B" was a molybdenum-impregnated mordenite (MOR) catalyst (ie, 2% Mo / MOR catalyst). Specifically, 1.32 g of ammonium heptamolybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O) was dissolved in 32 g of distilled water to obtain a clear solution. Next, a clear solution is added, mixed with 36 g of catalyst "A" (prepared as described above), dried at 329 ° F. (165 ° C.) for about 3 hours, and then at about 950 ° F. (510 ° C.) Firing for 4 hours gave an impregnated catalyst (ie catalyst "B").

Catalyst "C" was molybdenum-impregnated beta (BEA) zeolite (ie, 2% Mo / BEA catalyst). 64 g of beta catalyst (80% sieve / 20% Al ₂ O ₃ ) from H-β zeolite (sold from PQ Corporation (Valley Forge, Pennsylvania)), 22 g of distilled water and Al ₂ O ₃ solution (9.3% solids in water) ) And 172 g (sold as alumina solution from Criterion). The mixture was dried at 329 ° F. (165 ° C.) for about 3 hours and then calcined at 950 ° F. (510 ° C.) for about 4 hours. After firing, the catalyst was granulated and passed through a 14/40 sieve. An aqueous solution of ammonium heptamolybdate containing 0.784 g was mixed with 21.3 g of the beta catalyst prepared, dried at 329 ° F. (165 ° C.) for about 3 hours, and then calcined at 950 ° F. (510 ° C.) for about 4 hours. To give the impregnated catalyst (ie catalyst "C").

Catalyst "D" was a molybdenum-impregnated USY zeolite (ie, 5% Mo / USY catalyst). 80 g of H-USY zeolite (sold from UOP, Inc. (Des Plaines, lilinois) under the trade name "LZY-84") Al ₂ O ₃ solution (9.3% solids in water) (sold as alumina solution from Criterion) Mixing with 215 g produced USY catalyst (80% sieve / 20% Al ₂ O ₃ ). The mixture was then dried at 329 ° F. (165 ° C.) for about 3 hours and then calcined at 950 ° F. (510 ° C.) for about 4 hours. After firing, the catalyst was granulated and passed through a 14/40 sieve. An aqueous solution of ammonium heptamolybdate containing 2.35 g was mixed with 25 g of the prepared USY catalyst, dried at 329 ° F. (165 ° C.) for about 3 hours, and then calcined at 950 ° F. (510 ° C.) for about 4 hours. , Impregnated catalyst (ie catalyst "D") was obtained.

Example  2

This example demonstrates the ability to convert nitration-grade toluene of the same catalyst impregnated with a mordenite catalyst (catalyst "A" of Example 1) and molybdenum (catalyst "B" of Example 1) to benzene and xylene To illustrate. In each run, before introducing the liquid feed, the ground catalyst is placed in a 3 / 4-inch tube-shaped stainless steel, plug-flow reactor and pounds per 200 square inch gauge for 2 hours at 400 ° C. (752 ° F.). (psig) (about 1.4 megapascals (MPa)) flowing hydrogenation. The feed stream was a mixture of hydrogen and toluene (4: 1 hydrogen: toluene molar ratio), reaction conditions were 400 ° C. (752 ° F.) and 200 psig (about 1.4 MPa) and WHSV 1.0 and 2.0 for catalyst “A”. And WHSV 1.0, 2.0 and 5.0 for catalyst "B". Table 1 shows the analysis of the liquid feed (wt% feed) and product (Pdt. Wt%) obtained in each run.

Feed weight% Catalyst "A" Pdt. weight% Catalyst "B" Pdt. weight% WHSV 1.0 2.0 1.0 2.0 5.0 A hard gas 0.01 0.54 0.38 3.48 2.90 0.87 benzene 0.00 17.51 13.59 23.29 23.35 13.48 toluene 99.76 58.49 65.06 43.30 44.17 66.93 Ethylbenzene 0.05 0.36 0.38 0.33 0.32 0.21 p-xylene 0.04 4.86 4.20 5.78 5.72 4.01 m-xylene 0.06 10.58 9.12 12.67 12.51 8.70 o-xylene 0.00 4.65 3.97 5.55 5.49 3.80 Propylbenzene 0.00 0.01 0.01 0.01 0.01 0.00 Methylethylbenzene 0.00 0.65 1.10 0.34 0.40 0.55 Trimethylbenzene 0.00 2.18 1.91 4.76 4.70 1.32 A ₁₀₊ 0.09 0.18 0.17 0.46 0.44 0.13

The conversion of toluene is determined by dividing the difference in the amount of toluene in the feed and product by the toluene present in the feed. For example, using data obtained by proceeding with catalyst "A" and WHSV 2.0, the toluene conversion was about 34.8 (ie, 34.8 = 100 x (99.76-65.06) / 99.76). The selectivity of any particular component in the product is determined by dividing the yield of the component by the conversion of toluene. Thus, for example, using data obtained by proceeding with catalyst "A" and WHSV 2.0, benzene selectivity is about 39% (ie, 39 = 100 x (13.59 ÷ 34.8)) and xylene isomeric selectivity is about 49.7% (ie, 49.7 = 100 x 17.29 ÷ 34.8)).

For catalyst "B", the conversion was almost the same in WHSV 1 and 2, indicating that the catalyst is nearly equilibrium. The data show that the increase in WHSV results in lower conversion of toluene (57%, 56%, 33% for WHSV 1, 2, and 5 respectively) when using catalyst "B". This trend is also indicated by the data (41% to 35% for each of WSHV 1 and 2) when using catalyst "A". Based on the profile of the product produced with each catalyst, adding 2% by weight of molybdenum oxide generally did not significantly affect the production of one particular component (selectivity) over another component. This is easy to see. In WHSV 5, benzene and xylene selectivity obtained using catalyst "B" were 40.8 and 49.8, respectively, and very similar to those obtained using catalyst "A". The addition of 2% molybdenum oxide increased the catalyst activity by about 2.5 times compared to the catalyst "A". The yield of the by-product light gas is higher, while the heavy aromatics are lower, indicating a slightly higher yield of almost undesirable products.

Example  3

This example shows a C ₉ aromatic-comprising feed of the same catalyst impregnated with a mordenite catalyst (catalyst “A” in Example 1) and molybdenum (catalyst “B” in Example 1) as the xylene isomer. Illustrate the performance of% conversion.

The composition of the feed is shown in Table 2 below and was the same in each of the five runs. In each run, the catalyst was placed in a 3 / 4-inch tubular stainless steel, plug-flow reactor and introduced at 400 ° C. (752 ° F.) and 200 psig (about 1.4 MPa) before introducing the liquid feed. Flow hydrogenated during the process. The feed stream was a mixture of hydrogen and hydrocarbons in a 4: 1 molar ratio and reaction conditions were 400 ° C. (752 ° F.), 200 psig (about 1.4 MPa). WHSV for two runs with catalyst A were 1.0 and 1.5, while WHSV for three runs with catalyst "B" was 1.0, 1.5, and 2.0. The analysis of the liquid feed and product obtained at each run is shown in Table 2 below.

Feed weight% Catalyst "A" Pdt. weight% Catalyst "B" Pdt. weight% WHSV 1.0 1.5 1.0 1.5 2.0 A hard gas 0.20 2.86 2.04 12.48 9.09 10.61 benzene 0.12 2.09 1.98 5.15 4.90 4.47 toluene 0.01 9.81 7.84 23.44 23.50 21.51 Ethylbenzene 0.05 3.05 2.55 0.52 0.89 1.69 p-xylene 0.19 1.91 1.31 8.38 8.53 7.96 m-xylene 0.47 4.05 2.76 18.28 18.72 17.34 o-xylene 0.32 1.90 1.38 8.01 8.18 7.55 Propylbenzene 6.62 0.69 1.26 0.00 0.00 0.00 Methylethylbenzene 49.32 30.67 35.00 1.31 2.19 4.07 Trimethylbenzene 41.77 33.40 35.80 18.67 19.50 19.06 A ₁₀₊ 0.94 9.59 8.08 3.76 4.55 5.60

Based on the data shown in Table 2 above, unexpected surprising results are obtained with the catalyst "B". For example, unexpectedly and surprisingly, a high conversion of the feed is obtainable using catalyst "B" compared to catalyst "A". Specifically, the liquid product has a weight ratio of the C ₉ aromatics present in the C ₉ aromatic versus product present in the feed is from about 1.51 in WHSV 1.0 (i.e., 97.71 / 64.76) is obtained when using the catalyst "A", WHSV 1.5 to 1.35 (ie 97.71 / 72.06). In contrast, except for the use of catalyst "B", the liquid product obtained when passing the same feed under the same reaction conditions has a weight ratio of C ₉ aromatics present in the feed to C ₉ aromatics present in the product, WHSV 1.0 At about 4.89 (ie 97.71 / 19.98), and WHSV 1.5 to 4.5 (ie 97.71 / 21.69). This unexpectedly high conversion is beneficial in that there is a smaller amount of unreacted C ₉ aromatics that need to be recycled to the reactor for conversion. Although the addition of molybdenum is expected to increase the lifetime (activity) of the catalyst, it is unexpected and surprising that the addition of molybdenum results in a high conversion of C ₉ aromatics to xylene isomers.

Moreover, surprising and unexpected high conversion of C ₉ aromatics to xylene isomers is obtainable using catalyst "B" when compared to catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of xylene isomers to C ₉ aromatics ranging from WHSV 1.0 to about 0.12 (ie, 7.86 / 64.76), and WSHV 1.5 to 0.08 (5.45 / 72.06). Have In contrast, the liquid product obtained when using the catalyst "B" to pass the same feed under the same reaction conditions has a weight ratio of xylene isomer to C ₉ aromatics of about 1.74 (ie 34.67 / 19.98) at WHSV 1.0, And 1.63 (35.43 / 21.69) in WHSV 1.5.

Similarly, the data in Table 2 show surprising and unexpected high conversion of methylethylbenzene using catalyst "B" when compared to catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of methylethylbenzene present in the feed to methylethylbenzene present in the product from WHSV 1.0 to about 1.61 (ie 49.32 / 30.67), and WHSV 1.5 to 1.41 (ie 49.32 / 35). In contrast, the liquid product obtained when using the catalyst "B" to pass the same feed under the same reaction conditions yields a weight ratio of methylethylbenzene present in the feed to methylethylbenzene present in the product at about WHSV 1.0. 37.65 (ie 49.32 / 1.31), and WHSV 1.5 to 22.58 (ie 49.32 / 2.19). This unexpectedly high conversion is beneficial in that there is a smaller amount of unreacted methylethylbenzene that needs to be recycled to the reactor for conversion.

Moreover, the liquid product obtained when using catalyst "A" has a weight ratio of xylene isomers to ethylbenzene from WHSV 1.0 to about 2.58 (ie 7.86 / 3.05), and WHSV 1.5 to 2.14 (ie 5.45 / 2.55). Have In contrast, the liquid product obtained when using the catalyst “B” to pass substantially the same feed under the same reaction conditions yields a weight ratio of xylene isomer to methylbenzene at about 66.67 (ie 34.67 / 0.52) at WHSV 1.0. , And WHSV 1.5 at 39.81 (ie 35. 43 / 0.89). This unexpected and surprisingly high conversion rate is beneficial in downstream processes when the product stream is fractionated into its main components, namely aromatics containing 6, 7, 8, and 9 carbons as described above. Typically, further processing of the C ₈ aromatic fraction will essentially comprise an energy-consuming process of ethylbenzene. However, if there is substantially no ethylbenzene in the liquid reaction product obtained when using catalyst "B", and thus substantially no ethylbenzene in the C ₈ aromatic fraction, the energy-consuming process is not necessary to remove the fraction of ethylbenzene. . One of the advantages obtained using catalyst "B" to catalyst "A" under given reaction conditions and given feed.

In addition, the product obtained using catalyst "B" has a surprising and unexpectedly high weight ratio of xylene isomers to C ₁₀ aromatics compared to the product obtained using catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of xylene isomer to C ₁₀ aromatics of about 0.82 (ie, 7.86 / 9.59) in WHSV 1.0 and 0.67 (ie, 5.45 / in WHSV 1.5). 8.08). In contrast, a liquid product obtained by passing the same feed under the same reaction conditions using catalyst “B” yields a weight ratio of xylene isomers to C ₁₀ aromatics from WHSV 1.0 to about 9.22 (ie 34.67 / 3.76), and WHSV 1.5 to 7.79 (ie 35.43 / 4.55). This high proportion is a disproportionation reaction in which the dominant reaction involving C ₉ aromatics results in xylene isomers, and not a reaction yielding C ₁₀ aromatics and benzene. In addition, the absence or a small amount of C ₁₀ aromatics in the product and / or intermediate product streams means that the unreacted or produced C ₁₀ aromatics that need to be recycled to the feed for conversion have a small amount to conserve energy. It is advantageous in terms of reducing capital costs. As long as the C ₁₀ aromatics are in the intermediate or product stream, the C ₁₀ aromatics are tetramethylbenzenes which can be dominantly recycled and further converted to xylene isomers. Advantageously, in contrast to the product obtained with catalyst "A", the C ₁₀ aromatics present in the product obtained with catalyst "B" do not comprise ethyldimethylbenzene and / or diethylbenzene, both of which are It is more difficult to convert to the xylene isomer and can hardly be recycled.

The product obtained with catalyst "B" also has a surprising and unexpectedly high weight ratio of trimethylbenzene to methylethylbenzene compared to the product obtained with catalyst "A". Specifically, the liquid product obtained when using the catalyst "A" shows the weight ratio of trimethylbenzene to methylethylbenzene in WHSV 1.0 to about 1.1 (ie 33.4 / 30.67), and WHSV 1.5 to 1.0 (ie 35.8 / 35.0). ) In contrast, the liquid product obtained by passing the same feed under the same reaction conditions using catalyst “B” yields a weight ratio of trimethylbenzene to methylethylbenzene from WHSV 1.0 to about 14.25 (ie, 18.67 / 1.31) and WHSV 1.5 At 8.9 (ie 19.5 / 2.19). This unexpectedly high ratio is advantageous because trimethylbenzene is more readily convertible to xylene isomers than methylethylbenzene, and as a result is easier to recycle.

Moreover, the product obtained using catalyst "B" has a surprising and unexpectedly high weight ratio of benzene to ethylbenzene compared to the product obtained using catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of benzene to ethylbenzene from WHSV 1.0 to about 0.69 (ie 2.09 / 3.05) and WHSV 1.5 to 0.78 (ie 1.98 / 2.55). . In contrast, the liquid product obtained when using the catalyst "B" to pass the same feed under the same reaction conditions yields a weight ratio of benzene to ethylbenzene at WHSV 1.0 to about 9.9 (ie, 5.15 / 0.52), and at WHSV 1.5 5.51 (ie, 4.9 / 0.89).

The results shown in Table 2 above for the toluene disproportionation reaction illustrate that addition of 2% molybdenum oxide increases the activity of the catalyst, as evidenced by higher methylethylbenzene and trimethylbenzene conversion under the same conditions. . Returning to the results obtained in Example 2 above, the selectivity obtained using the catalysts "A" and "B" for the toluene disproportionation reaction was about the same or slightly worse than that of the catalyst "B". The data reported in Table 3 below show that, for the conversion of C ₉ aromatics, the selectivity for xylene is slightly higher, the selectivity for benzene is slightly lower, and the selectivity for C _{10 +} aromatics is significantly lower.

Catalyst "A" Catalyst "B" WHSV 1.0 1.5 1.0 1.5 2.0 A ₉ transition 32.9 21.2 79.6 77.8 76.3 Selectivity to xylene 24.0 21.2 43.6 45.5 42.7 Selectivity to Benzene 6.4 7.8 6.5 6.2 5.9 Selectivity for A ₁₀₊ 29.2 31.6 4.7 5.6 7.3 Selectivity to ethylbenzene in A ₈ 28.0 23.8 1.5 2.5 4.9

When catalyst "B" is used the amount of ethylbenzene present in the C ₈ aromatic fraction is significantly lower than the amount present in the same fraction obtained using catalyst "A". Thus, the C ₈ aromatic fraction obtained using catalyst "B" is even more suitable as chemical feedback for the production of para-xylene. Being present in the resulting product stream by using the catalyst "B" C _{10 +} aromatics are recycled to the process, it has been found that it is possible to generate more of the xylenes. Alternatively, the presence of the C _{10 +} aromatics, which in the product stream that is obtained by using the catalyst "A", the fraction, for particular C _{10 +} aromatics (for example, does not switch to facilitate a xylene isomer, ethyl dimethyl benzene and Diethylbenzene), which cannot be recycled and will quickly deactivate the catalyst. When using the catalyst "A", many methyl ethyl benzene is reacted to form diethyl -C _{10 +} aromatics and toluene or ethyl benzene, dimethyl ethyl benzene. However, when using the catalyst "B", methylethylbenzene deactivates the ethyl group and saturates the group to give ethane with the production of toluene. Almost no ethylbenzene is formed, and toluene reacts with trimethylbenzene, which is also present in the feed, to produce two xylene molecules. Heavy aromatics is an equilibrium distribution of tetramethylbenzene which reacts with toluene to give further xylene isomers.

Example  3-A (catalyst " A "  Steady-state operation)

The above-described embodiment shows the conversion obtainable in a single pass. Recirculation can also be used to measure or evaluate the conversion obtainable in a steady state process. The recycle yield in the process with catalyst "A" was determined by process modeling based on the results shown in Table 2 above. A process flow scheme based on the modeling is shown in FIG. 2.

With respect to FIG. 2, the process flow, generally designated 50, comprises a distillation train defined by reactor 52 and liquid product separator 54 and multiple distillation columns 56A, 56B, 56C, and 56D. Generally, the C ₉ aromatic-comprising feed and hydrogen gas are passed through line 58 to enter reactor 52 where the feed is catalytically reacted (catalyst "A") in the presence of hydrogen gas to obtain an intermediate product Leaving reactor 52 via intermediate product line 60 and then into liquid product separator 54. That is, separator 54 separates the light hydrocarbons (typically gas) from aromatics (typically liquid), the light hydrocarbons leave the process flow via line 62, and the aromatics leave the separator 54 through line 64 to distill the first distillation. Entering column 56A where the aromatics are separated into two fractions, one of which predominantly contains benzene and toluene, and the other containing higher aromatics (including xylene). The fraction containing benzene and toluene passes through line 66 out of distillation column 56A and into second distillation column 56B, while the higher aromatic fraction passes out line distillation column 56A through line 68 and into third distillation column 56C. Second distillation column 56B separates the incoming feed into fractions predominantly containing benzene 70 and toluene 72. Both fractions can ultimately be recycled, whereby the second distillation column can be removed together such that only the toluene fraction 72 (which may contain some benzene) is recycled, as indicated. A third distillation column 56C separates the incoming feed into fractions which predominantly contain the desired xylene isomer product 74 and the C _{9 +} aromatics 76. That is, C _{9 +} aromatic fraction 76 is fed to fourth distillation column 56D, the feed of which is recycled fraction 78 of unreacted C ₉ aromatics and heavy C _{10 +} aromatic byproduct fraction 80 (typically multiply substituted methyl and Containing a mixture of ethyl aromatics).

Returning to Table 2 above, for catalyst "A" in WHSV 1.0, the selectivity of the methyl group in the C ₉ feed to the non-C ₉ product is as follows: 6% with light non-aromatic; 26% with toluene; 36% with xylene; And 32% as aromatic in C _{10 +} . Since neither light non-aromatics nor aromatics in C ₁₀₊ are recycled in the process flow 50 shown in FIG. 2, the fraction is not available for eventually converting to mixed xylenes. The selectivity of the aromatic ring to the non-C ₉ product in the C ₉ feed is as follows: 69% by BTX; 10% with ethylbenzene; And 21% as aromatic in C _{10 +} . Using 100 pounds of C ₉ feed (Ibs.), There would be 1.49 pound-moles (Ibmoles) of methyl groups in the feed and 0.822 Ibmoles of aromatic rings in the feed. The next step is to calculate if the availability of methyl or benzyl groups limits the production of xylene isomers. The xylene potential of the methyl group is determined by multiplying the molar amount of the methyl group in the feed by the average total sum of the selectivity of the methyl group relative to the toluene and xylene produced:

1.49 Ibmoles x (0.26 + 0.36) ÷ 2 = 0.462 Ibmoles.

Similarly, the xylene potential of the benzyl group is determined by multiplying the molar amount of the benzyl group by the selectivity to BTX in the product of the aromatic ring in the feed:

0.822 Ibmoles x 0.69 = 0.567 Ibmoles.

Based on the foregoing, the availability of methyl groups limits the production of xylene. Based on this, the recycle yield on the molar basis is: 0.462 Ibmoles xylene; 0.105 Ibmoles benzene (difference of 0.567 and 0.462); 0.082 Ibmoles ethylbenzene; And 0.173 Ibmoles C _{10 +} . Based on the relative weight, including hard non-aromatic, it is: 9% hard non-aromatic; 8% benzene; 49% xylene; 9% ethylbenzene; And aromatic in 25% C ₁₀₊ .

Example  3-B (catalyst '' B "  Steady state operation)

The recycle yield in the steady state process with catalyst "B" was similarly determined by process modeling based on the results shown in Table 2 above. A process flow scheme based on this modeling is shown in FIG. 3, except that different conversions are obtainable.

With respect to FIG. 3, the process flow, generally designated 90, includes distillation trains defined in reactor 52 and liquid product separator 54 and multiple distillation columns 56A, 56B, and 56C. In general, the C ₉ aromatic-comprising feed and hydrogen gas are passed through line 58 to enter reactor 52 where the feed is catalytically reacted (catalyst “B”) in the presence of hydrogen gas to obtain an intermediate product. This intermediate product is different from that obtained using catalyst "A". This intermediate product leaves reactor 52 via intermediate product line 60 and then enters liquid product separator 54. That is, separator 54 separates the light hydrocarbons (typically gas) from aromatics (typically liquid), the light hydrocarbons leave the process flow via line 62, and the aromatics leave the separator 54 through line 64 to distill the first distillation. Enter column 56A. Here, the aromatic is separated into two fractions, one of which predominantly contains benzene and toluene, and the other contains higher aromatics (including xylene). The fraction containing benzene and toluene passes through line 66 out of distillation column 56A and into second distillation column 56B, while the higher aromatic fraction passes out line distillation column 56A through line 68 and into third distillation column 56C. Second distillation column 56B separates the incoming feed into fractions predominantly containing benzene 70 and toluene 72. Both fractions can ultimately be recycled, whereby the second distillation column can be removed together such that only the toluene fraction 72 (which may contain some benzene) is recycled, as indicated. The third distillation column 56C separates the (as recycle to reactor 52) fraction 76 containing fraction 74 and C _{9 +} aromatic containing xylene isomers product desired incoming feed.

Returning to Table 2 above, for the catalyst "B" in WHSV 1.0, the selectivity of the methyl group in the C ₉ feed to the non-C ₉ product is as follows: 0% with light non-aromatic; 25% with toluene; 65% with xylene; And 11% of the aromatic C _{+ 1O.} Since C _{+ 1O} is an aromatic, all of the substituted methyl, which continuously produces a xylene to react with benzene and toluene. There is no methyl group lost as a byproduct in process flow 90. The selectivity of the benzyl group in the C ₉ feed to the non-C ₉ product is as follows: 96% by BTX; 1% with ethylbenzene; And 3% as aromatic in C _{10 +} . Using 100 lbs of C ₉ feed, there would be 1.49 Ibmoles of methyl in the feed and 0.822 Ibmoles of benzyl in the feed. The next step is to calculate if the availability of methyl or benzyl groups limits the production of xylene isomers. The calculation is performed in the manner described above in Example 3-A. The xylene potential of the methyl group is 0.745 Ibmoles, while the xylene potential of the benzyl group is 0.814 Ibmoles. Based on this, the recycling yield on a molar basis is calculated as follows: 0.745 Ibmoles xylene; 0.069 Ibmoles benzene (difference of 0.814 and 0.745); And 0.008 Ibmoles ethylbenzene. Based on relative weight, including hard non-aromatics: 15% hard non-aromatics; 5% benzene; 79% xylene; 1% ethylbenzene; And 0% C _{10 +} heavy aromatics.

A comparison of the recycle yields obtained in Examples 3-A and 3-B is summarized in Table 4 below.

Recycle yield (%) Catalyst "A" Catalyst "B" A hard gas 9 15 benzene 8 5 Xylene 49 79 Ethylbenzene 9 One C _{10 +} 25 0 EB% in C ₈ aromatics 15.5 1.3

Example  4

This example comprises about 61% by weight of a C ₉ aromatic (A ₉ ) hydrocarbon and toluene of the same catalyst (catalyst “B” in Example 1) impregnated with a mordenite catalyst (catalyst “A” in Example 1) and molybdenum The ability to convert a feed comprising about 38% by weight to xylene isomers is illustrated. Two separate runs were performed using the same feed. In each run, the catalyst was placed in a 3 / 4-inch tube-shaped stainless steel, plug-flow reactor and for 2 hours at 400 ° C. (752 ° F.) and 200 psig (about 1.4 MPa) before introducing the liquid feed. Treated with flowing hydrogen. The feed stream was a mixture of hydrogen and hydrocarbons in a 4: 1 molar ratio and the reaction conditions were set at 400 ° C. (752 ° F.), 200 psig (about 1.4 MPa) at WHSV 1.0. Analysis of liquid feeds and products is shown in Table 5 below.

Feed weight% Catalyst "A" Pdt. weight% Catalyst "B" Pdt. weight% A hard gas 0.19 2.99 10.30 benzene 0.18 3.43 11.33 toluene 37.51 34.64 32.12 Ethylbenzene 0.04 3.00 0.55 p-xylene 0.11 3.45 7.70 m-xylene 0.28 7.25 16.87 o-xylene 0.19 3.23 7.33 Propylbenzene 3.99 0.26 0.00 Methylethylbenzene 30.75 18.02 0.93 Trimethylbenzene 26.08 18.89 11.29 A ₁₀₊ 0.54 4.83 1.58

Reaction conditions for this example are the same as those used in Example 3. Thus, as long as the mixed toluene / C9 aromatic feed reacts under the same process conditions and starts with pure C9 aromatic feed and the resulting toluene, the toluene can be recycled to the process for further production of xylene. It is easy to identify. In the recycle operation, only products are light gases, benzene and xylene. Both catalysts can simultaneously convert toluene and C9 aromatics, while for catalyst "A", the reaction of toluene and C9 aromatics results in a C8 aromatic product being disadvantageously high in ethylbenzene-about 17.8% (ie 17.8 = 100 x (3.00 / (3.00 + 3.45 + 7.25 + 3.23)) Thus, processing the C9 aromatics with toluene can produce additional xylenes, while being used as chemical feedback in the production of para-xylene The quality of xylene for is poor, i.e., xylene produced from toluene is much lower quality than xylene produced by toluene disproportionation reaction, but produced from the same feed using catalyst "B". The C8 aromatics are beneficially and unexpectedly surprisingly low in ethylbenzene-about 1.7% (ie, 1.7% = 100 x (0.55 / (0.55 + 7.70 + 16.87 + 7.33)), resulting in chemical feedback in para-xylene production. to Resulting in higher quality xylene products that are more suitable.

Moreover, many other unexpected and surprising results are obtained when using catalyst "B". For example, surprising and unexpectedly high conversion of C ₉ aromatics to xylene isomers is obtainable using catalyst "B" compared to catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of the C ₉ aromatics present in the C ₉ aromatic versus product present in the feed of about 1.64 (i. E., 60.82 / 37.17). In contrast, the liquid product obtained when using the catalyst "B" to pass the same feed under the same reaction conditions results in a weight ratio of C ₉ aromatics present in the feed to C ₉ aromatics present in the product of about 4.98 (ie, 60.82 / 12.22). It is advantageous in that there is less amount of unreacted C ₉ aromatics that need to be recycled back to the reactor for this surprising and unexpected high conversion. Although addition of molybdenum is expected to increase the lifetime (activity) of the catalyst, it is unexpected and surprising that it results in such a high conversion of C ₉ aromatics to xylene isomers.

Moreover, surprising and unexpected high conversion of the feed is obtainable using catalyst "B" when compared to catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of xylene isomers to C ₉ aromatics of about 0.37 (ie 13.93 / 37.17). In contrast, the liquid product obtained when using the catalyst "B" and passing the same feed under the same reaction conditions has a weight ratio of xylene isomers to C ₉ aromatics of about 2.61 (ie 31.9 / 12.22).

Similarly, the data in Table 5 show surprising and unexpected high conversion of methylethylbenzene using catalyst "B" when compared to catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of methylethylbenzene present in the feed to methylethylbenzene present in the product at about 1.71 (ie 30.75 / 18.02). In contrast, using catalyst "B", the liquid product obtained when passing the same feed under the same reaction conditions results in a weight ratio of about 33.06 (i.e., methylethylbenzene present in the feed to methylethylbenzene present in the product). , 30.75 / 0.93). This unexpectedly high conversion is advantageous in that the amount of unreacted (or generated) methylethylbenzene that needs to be recycled to the reactor for conversion is smaller.

Moreover, the liquid product obtained when using catalyst "A" has a weight ratio of xylene isomers to ethylbenzene of about 4.64 (ie 13.93 / 3). In contrast, the liquid product obtained when using the catalyst "B" and passing the same feed under the same reaction conditions has a weight ratio of xylene isomer to ethylbenzene of about 58 (ie 31.9 / 0.55). As described above, this unexpectedly surprisingly high weight ratio is advantageous in downstream processes in which the product stream is fractionated into its main components, namely aromatics containing 6, 7, 8, and 9 carbons. Typically, further processing of the C ₈ aromatic fraction will essentially comprise an energy-consuming process of ethylbenzene. However, if there is substantially no ethylbenzene in the liquid reaction product obtained using catalyst "B" and therefore substantially no ethylbenzene in the C ₈ aromatic fraction, the energy-consuming process is not necessary to remove the fraction of ethylbenzene. .

The product obtained using catalyst "B" also has a surprising and unexpectedly high amount of xylene isomers to C ₁₀ aromatics compared to the product obtained using catalyst "A". Specifically, the liquid product obtained using catalyst "A" has a weight ratio of xylene isomers to C ₁₀ aromatics of about 2.88 (ie 13.93 / 4.83). In contrast, the liquid product obtained when using the catalyst "B" and passing the same feed under the same reaction conditions has a weight ratio of xylene isomer to C ₁₀ aromatics of about 20.19 (ie 31.9 / 1.58).

Moreover, the product obtained using catalyst "B" has a surprisingly unexpectedly high amount of trimethylbenzene to methylethylbenzene compared to the product obtained using catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of trimethylbenzene to methylethylbenzene of about 1.05 (ie 18.89 / 18.02). In contrast, the liquid product obtained when using the catalyst "B" through the same feed under the same reaction conditions has a weight ratio of trimethylbenzene to methylethylbenzene of about 12.14 (ie 11.29 / 0.93).

The product obtained using catalyst "B" has a surprisingly and unexpectedly high amount of benzene to ethylbenzene compared to the product obtained using catalyst "A". Specifically, the liquid product obtained when using catalyst "A" has a weight ratio of benzene to ethylbenzene of about 1.14 (ie, 3.43 / 3). In contrast, the liquid product obtained when using the catalyst "B" through the same feed under the same reaction conditions has a weight ratio of benzene to ethylbenzene of about 20.6 (ie 11.3 / 0.55).

The reported data indicates that about 80% of the C9 aromatics are converted using catalyst "B" (only about 39% as catalyst "A") and about 14% of toluene in the feed is catalyst "B" (catalyst "A" In comparison to only about 7.6%). Furthermore, a superficial comparison of the product stream shows the following using catalyst "B": (a) Almost all of the methylethylbenzenes were converted; (b) increased yields of benzene and xylene; (c) the concentration of ethylbenzene in the C ₈ aromatics is significantly lower; And (d) the yield of C ₁₀ aromatics is drastically reduced. Compared with the reaction of the C ₉ aromatic alone, there is no basic yield in the yield of toluene, while there is an increase in the yield of benzene. Thus, toluene can be co-processed with C ₉ aromatics if necessary, resulting in increased yield of benzene that can be recycled to the reactor.

Example  5

This example illustrates the performance of large pore-sized, molybdenum-impregnated zeolite catalysts. Specifically, this example relates to a molybdenum-impregnated, mordenite catalyst, which converts a feed comprising about 60% by weight C ₉ aromatic (A ₉ ) hydrocarbon and about 38% by weight toluene to xylene isomers. Illustrates the performance of catalyst "B" of Example 1, molybdenum-impregnated, beta zeolite (catalyst "C" of Example 1), and molybdenum-impregnated, USY zeolite (catalyst "D" of Example 1) . Four separate runs were performed using the same feed. In each run, the catalyst is placed in a 3 / -inch tubular, stainless steel, plug-flow reactor, and about 400 ° C. (752 ° F.), prior to introducing the liquid feed (unless otherwise indicated in the data shown below). And flow hydrotreated at 200 psig (about 1.4 MPa) for 2 hours. The feed stream was a mixture of hydrogen and hydrocarbons with a molar ratio of 4: 1 and the reaction conditions were set at 200 psig (about 1.4 MPa) at 400 ° C. (752 ° F.) (unless otherwise specified) at WHSV 1.0. Analysis of liquid feeds and products is shown in Table 6 below.

Feed weight% Catalyst "B" Pdt. weight% Catalyst "C" Pdt. weight% Catalyst "D" Pdt. weight% Catalyst "D" Pdt. weight%
Process temperature (℃) 750 751 750 771 A hard gas 0.2 10.3 11.3 9.6 8.2 benzene 0.1 11.3 7.8 4.8 4.5 toluene 38.4 32.1 29.3 32.3 33.4 Ethylbenzene 0.0 0.5 1.9 2.9 2.6 p-xylene 0.1 7.7 7.5 6.4 5.8 m-xylene 0.3 16.9 16.3 14.1 12.7 o-xylene 0.2 7.3 7.1 6.2 5.7 Propylbenzene 4.1 0.0 0.0 0.3 0.5 Methylethylbenzene 30.3 0.9 3.6 7.9 9.4 Trimethylbenzene 25.6 11.3 11.7 11.0 12.2 A ₁₀₊ 0.7 1.6 3.5 4.5 5.0

The data shown in the above table shows that not only molybdenum-impregnated mordenite catalyst (catalyst "B") but also other pore-sized molybdenum-impregnated zeolites (catalysts "C" and "D") are also C ₉ aromatic- It is shown that it performs preferably well in converting the inclusion feed to the xylene isomer. Indeed, the other pore-sized molybdenum-impregnated zeolites also contain xylene isomers versus ethylbenzene, xylene isomers to C ₉ aromatics (eg, methylethylbenzene), xylene isomers to C ₁₀ aromatics, trimethylbenzene Results in an unexpectedly high ratio of to methylethylbenzene, benzene to ethylbenzene, and in the production of a conversion, leads to a high conversion of C ₉ aromatics and methylethylbenzene.

The foregoing description is for the purpose of clarity of understanding only, and is not intended to place unnecessary limitations therefrom, and modifications within the scope of the invention may be apparent to those skilled in the art.

Claims (1)

Method for preparing xylene isomers comprising:
(a) contacting the C ₉ aromatic-comprising feed with a catalyst under conditions suitable to convert the C ₉ aromatic-comprising feed into an intermediate product stream comprising xylene isomers;
(b) separating at least some of the xylene isomers from the intermediate product stream; And,
(c) recycling the xylene isomer-free intermediate product stream obtained in step (b) to the feed of step (a).

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